FIELD OF THE INVENTION
This invention relates generally to data transmission in an avionics system primarily for aircraft and the like. More specifically, this invention relates to a programmable digital circuit device for use in conjunction with a time-division multiplexed data bus system.
Increasing avionics system complexity in modern military aircraft is demanding an increasing proportion of the resources available for aircraft weapon systems. Although greater sophistication in avionics provides increased capability and accuracy for an aircraft weapon system, is also a substantial cause of decreased reliability in the overall weapons system. Digital avionics, by being more orderly and systematic and by permitting growth and improvement without major hardware modification, provides the desired improvement in capabilities and performance without the usual concomitant decrease in reliability and increase in cost. Time-division multiplexed data bus techniques permit standard equipment interfaces and a standard approach to avionic data intercommunication thereby maximizing the advantages derived from a digital avionics system.
Time-division multiplex is the transmission of information from several signal channel subsystems through one communication bus with different channel samples staggered in time to form a composite pulse train. A remote terminal is the name commonly given the electronics necessary to provide an interface between the bus and a subsystem. A bus controller is the electronics that serves the function of commanding, scanning and monitoring bus "traffic" to prevent overlap and erroneous communications. In a typical aircraft avionics system that utilizes a time-division multiplexed data bus configuration, the subsystems might include: an inertial navigation unit, a fire control radar, a central air data computer, a fire control computer, a target identification set, a fire control navigation panel and one or more associated displays.